JP2008232678A - Core shroud replacement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten greatly a period from manufacture of a new core shroud until finish of a replacement work through conveyance into the core shroud and an apparatus assembly work. <P>SOLUTION: This method has a core shroud manufacturing process for manufacturing the core shroud on an operation floor over a reactor pressure vessel, and performing installation of a load supporting plate of the core shroud; a core shroud installation process for suspending and installing the manufactured core shroud from the operation floor into the reactor pressure vessel; a load supporting plate carrying-out process for carrying out in a body the load supporting plate to the operation floor side after installation of the core shroud; and an incore apparatus assembly process for dividing an internal space of the core shroud into an upper side working domain and a lower side working domain based on an installation height position of a core support plate, and advancing an assembly work of incore apparatuses by accessing each working domain respectively individually. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for exchanging a core shroud installed in a reactor pressure vessel such as a boiling water reactor, and in particular, a core shroud replacement that significantly shortens the period from the production of a new shroud to the end of the exchanging operation. Regarding the method.

  Generally, a reactor core shroud of this type is constructed by welding stainless steel members, and cracks or the like due to stress corrosion cracks occur at or near the weld during long-term operation. When it is determined that the crack or the like has become difficult to deal with by partial repair, the core shroud itself needs to be replaced. Until now, replacement of the core shroud has been extremely sensitive to high activation in the reactor, so all operations such as cutting and removal of the core shroud and installation of the new shroud are performed by remote operation. It was.

  On the other hand, in recent years, the technology for removing pollutants in nuclear reactor facilities has advanced remarkably, and for example, it has become possible to clean a radiation-contaminated site extremely effectively using a chemical agent such as a permanganate solution. ing. By applying such a technique for reducing the radiation dose equivalent rate in the reactor, the core is cleaned, and a shroud replacement technique by workers other than remote work is possible.

  In this situation, we have experience in replacing core shrouds and in-core equipment for the reactor pressure vessels of the past four plants. In these cases, however, a construction period of about 300 days was required on a performance basis. There have been no reports on the replacement of the core shroud in foreign countries. As the background, it is mentioned that replacement of the core shroud takes a long work period.

  The past core shroud replacement method performed in our country will be described.

  The old core shroud and in-core equipment to be replaced are removed outside the reactor after the inside of the reactor pressure vessel is derailed. The new core shroud is manufactured on the lowest floor (F1) located on the side of the reactor pressure vessel. The reason for this is that while the new core shroud to be manufactured is set to a complete shape over the entire height, the space above the operation floor located above the reactor pressure vessel depends on the rail arrangement of the overhead crane, etc. This is because the height of the entire core shroud is restricted. When the new core shroud is manufactured on the lowermost floor (F1), it is necessary to move up and down the equipment and to / from the operation floor, and a certain time loss has occurred in the progress of the work.

  Further, a new core shroud manufactured by the above-described method has not been provided with a joining member around its upper end, such as a water supply sparger inlet pipe. All of the feed water sparger inlet pipes were installed after installing a new core shroud in the reactor pressure vessel, which required a certain amount of time for the welding operation and the like in the reactor.

  Further, after the new core shroud is manufactured, the core shroud is transported from the lower floor (F1) to the operation floor above the reactor pressure vessel, for example, a plurality of parts for maintaining the shape of the shroud wall against the load at a plurality of locations. Attach or attach any of the transport plates such as support plates, cameras, welding machines, etc., and then transfer the core shroud from the operation floor to the reactor pressure vessel for installation. Had gone. For this reason, a certain time is required in the transfer route of the manufactured core shroud.

  In addition, after the core shroud was installed in the reactor pressure vessel, the support plates made up of a plurality of parts mounted on the core shroud were individually removed for each part, and they were individually carried out of the reactor. A certain amount of time has also been spent on removing and carrying out such a multi-part outfitting.

  Furthermore, when assembling in-core equipment in the core shroud, the access route from the opening above the core shroud is applied to any of the upper and lower spaces in the reactor. For this reason, the basic assembly procedure is a so-called bottom-up method in which work starts from the inner bottom side of the core shroud and sequentially moves upward. For this reason, in-furnace in-furnace equipment, interference between one work and another work may occur, resulting in inefficiency. Moreover, since the space in the core shroud is divided into upper and lower parts after the core support plate is installed, the work is further complicated and the work time is long.

Conventionally known techniques include a core shroud replacement method by the applicant of the present application (see, for example, Patent Documents 1 and 2).
JP-A-8-152495 JP 2000-249791 A

  As described above, in the conventional technology, since the new core shroud is manufactured on the lowest floor (F1) located on the side of the reactor pressure vessel, it is necessary to move up and down the equipment, to and from the operation floor, A certain amount of time was lost in the progress of the work.

  In addition, a new core shroud manufactured by the above-described method is not attached with a joining member around its upper end in advance, and all the members are formed after the new core shroud is installed in the reactor pressure vessel. Therefore, a certain amount of time was required for processes such as welding in the furnace.

  In addition, after the production of the new core shroud, the support plate is installed from the lower floor (F1) through the operation floor above the reactor pressure vessel. Time was spent on the route to transfer to.

  In addition, after the core shroud was installed in the reactor pressure vessel, the support plate consisting of multiple parts mounted on the core shroud was individually removed for each part and carried out of the reactor. Also time was spent.

  In addition, when assembling the in-core equipment in the core shroud, the access route from the opening above the core shroud was applied to both the upper and lower spaces in the reactor, so the assembly procedure was performed in order from the inner bottom side of the core shroud. Since the bottom-up system has shifted to the bottom, the in-core equipment interferes with each other, resulting in inefficiency, and after the core support plate is installed, the space inside the core shroud is divided into upper and lower parts, further work. It became complicated and the working time was long.

  The present invention has been made in view of such circumstances, and greatly shortens the period from the manufacture of a new core shroud to the transfer into the core shroud and the assembly of the equipment to the end of the replacement work. It is an object of the present invention to provide a method for replacing a core shroud that can be used.

  In the present invention, in order to solve the above-described problems, a core shroud replacement method for assembling in-core equipment by installing a new core shroud in a reactor pressure vessel in which the reactor is derailed and the core shroud is removed. A core shroud is manufactured on the operation floor above the reactor pressure vessel, and a core shroud manufacturing process for mounting a load support plate of the core shroud, and the manufactured core shroud from the operation floor A core shroud installation process suspended and installed in a reactor pressure vessel; a load support plate unloading process for unloading the load support plate to the operation floor side after the core shroud is installed; and a core shroud The upper work area and the lower work are defined based on the installation space position of the core support plate. Divided into a region, it provides a core shroud replacement method characterized by comprising the these furnace equipment assembly process, each to advance the assembly of the furnace equipment to access individually to each work area.

  According to the present invention, the production location and configuration of a new core shroud, the transport of the produced core shroud and installation into the reactor pressure vessel, the loading of the loaded load support plate, and the upper and lower regions within the core shroud As a result of parallel assembly work of in-furnace equipment, work time can be shortened in each process such as production, transfer, introduction / removal into the furnace, equipment assembly, etc., and transportation from the production of a new core shroud into the core shroud In addition, it is possible to greatly shorten the period until the replacement work is completed through the equipment assembly work.

  Hereinafter, an embodiment of a core shroud replacement method according to the present invention will be described with reference to the drawings. In the following description, the process from the process of manufacturing a new core shroud to the process of installing the manufactured new core shroud in the reactor pressure vessel and completing the assembly of the in-core equipment will be described.

(1) Core shroud manufacturing process (Figure 1)
FIG. 1 is a longitudinal sectional view showing a configuration of a core shroud newly manufactured and a manufacturing situation thereof as a core shroud manufacturing process. As shown in FIG. 1, in this embodiment, an operation floor 1 disposed above the reactor pressure vessel is applied as a manufacturing place. In the core shroud manufacturing process, the assembling work is assembled as a cylindrical core shroud 2 having a certain height by welding plate-like components constituting the core shroud 2. In addition, all assembly work including fitting of various jigs is performed on the operation floor 1.

  An opening 3 located above the reactor pressure vessel 13 is disposed on the operation floor 1, and the manufactured core shroud 2 can be transferred into the reactor pressure vessel 13 from the opening 3. A crane 4 and its guide rail 5 are arranged above the operation floor 1, and the crane 4 is provided with a wire 6 and a hanging hook 7. The manufactured core shroud 2 can be moved using this crane 4.

  The new core shroud 2 is substantially the same as the core shroud 2 before replacement (not shown). However, in this embodiment, a water sparger inlet pipe is provided at the upper end of the core shroud 2 as a structure manufactured on the operation floor 1. Install 8. The feed water sparger inlet pipe 8 is provided in a state of projecting above the trunk portion of the core shroud 2 and is connected to a feed water inlet nozzle that penetrates the reactor wall of the reactor pressure vessel 13 in a later step. That is, in this embodiment, the water supply sparger inlet pipe 8 is attached to the upper end of the core shroud 2, and in the subsequent core shroud installation process, the water supply sparger inlet pipe 8 and the core shroud 2 are integrated into the reactor pressure vessel 13. Built in.

  By the way, due to the connection of the water supply sparger inlet pipe 8, the height of the core shroud 2 including the water supply sparger inlet pipe 8 becomes a constant height. On the other hand, due to the arrangement of the guide rails 5, the work space on the operation floor 1 has a certain height restriction. Therefore, in the present embodiment, in the core shroud manufacturing process, the overall height is lowered except for a part of the lower end portion constituent material of the core shroud 2 to be manufactured. Specifically, as shown by the phantom line in the lower part of FIG. 1, the connection of the short ring 9 serving as the lowermost component of the core shroud 2 is omitted. Thereby, the margin of the height of the upper space of the operation floor 1 by the attachment of the water supply sparger inlet pipe 8 is ensured. And the short ring 9 which is a lower end part constituent material of the core shroud 2 removed in the core shroud manufacturing process is connected to a shroud support member in the furnace in a core shroud installation process described later.

  Further, as shown in FIG. 1, on the inner peripheral side of the core shroud 2 to be manufactured, a load supporting plate composed of a plurality of ring-shaped members arranged vertically, that is, an upper load supporting plate 10 and a lower load supporting member. A plate 11 is mounted. The upper load support plate 10 is disposed on the upper ring of the core shroud 2, and the lower load support plate 11 is disposed on the lower ring of the core shroud 2. Further, a shroud suspension 12 is disposed at the upper end position of the core shroud 2.

  In the above core shroud manufacturing process, the operation floor 1 disposed above the reactor pressure vessel 13 is applied, and the core shroud 2 is fixedly disposed at a fixed position on the operation floor 1 and the shroud assembly and fitting are performed. Do all of the above.

  Therefore, as compared with the case where the core shroud 2 is manufactured on the lowest floor located on the side of the reactor pressure vessel 13, which is performed in the conventional method, the equipment is lifted and the operation floor 1 is moved. In addition, by joining the water supply sparger inlet pipe 8 around the upper end of the core shroud 2 in advance, the welding operation in the furnace after the conveyance can be omitted. Therefore, workability is improved as compared with the conventional case, and the manufacturing time can be shortened.

(2) Core shroud installation process (Figure 2)
FIG. 2 is an explanatory diagram illustrating a core shroud installation process in which the manufactured core shroud 2 is transported into the reactor pressure vessel 13 and the core shroud 2 is installed in the reactor pressure vessel 13.

  As shown in FIG. 2, the manufactured core shroud 2 is connected from the operation floor 1 to the reactor pressure vessel 13 by connecting the wire 6 of the crane 4 to the shroud suspension 12 mounted on the inner peripheral side of the upper end. Can be hung. A shielding member 14 is disposed on the inner peripheral surface portion of the reactor pressure vessel 13.

  On the control rod drive mechanism housing 15 at the bottom of the reactor pressure vessel, a horizontal jack stand base 16 and a reactor bottom scaffold are installed in advance, and a plurality of pillars 18 having jacks 17 stand on the periphery thereof. It is installed. The upper end of the column 18 is integrally connected to the lower load support plate 11 in the core shroud 2 introduced into the furnace, for example.

  A short ring 9 is welded and connected to the lower end of the lower shell of the core shroud 2 suspended in the reactor pressure vessel 13 and further connected to the shroud support 19 by welding (shroud H7 welding).

  Although the diffuser 21 and the like of the recirculation pump 20 are installed in the reactor pressure vessel 13 in advance, a predetermined recirculation nozzle (for example, N1 nozzle) 22 opened at the lower portion of the reactor pressure vessel 13 is opened. is doing. The recirculation nozzle is sized to allow an operator to pass through. Further, the baffle plate 23 and the shroud support 19 have gaps, and these gaps are sized to allow an operator to pass through and communicate with the recirculation nozzle. Therefore, the worker can access the inside of the reactor pressure vessel 13 from the outside through the recirculation nozzle.

  As described above, in this process, the shroud with a water supply sparger inlet pipe is suspended and installed.

(3) Load carrying plate unloading process (FIGS. 3 and 9)
FIG. 3 is an explanatory view showing a load supporting plate carrying-out process (a lifting tool integrated carrying-out process) in which the load supporting plate is integrally carried out to the operation floor 1 side after the core shroud 2 is installed.

  As described above, the load supporting plate which is a fitting is composed of a plurality of parts such as the upper load supporting plate 10 and the lower load supporting plate 11. Therefore, as shown in FIG. 3, in this process, the upper load supporting plate 10 and the lower load supporting plate 11 which are the fittings are stacked together, and the jack stand base 16 and the furnace bottom scaffold are integrally formed. Then, it is carried out to the operation floor 1 side by a hanging tool.

  FIG. 9 is a time chart for the work process with the time axis as the horizontal axis. As indicated by the reference numeral a1 in FIG. 9, the load supporting plate carrying out step and the shroud H7 welding step in the previous step require a certain amount of work time, but the upper load that is a fitting product. Since the supporting plate 10 and the lower load supporting plate 11 are stacked on each other, and the jack stand base 16 and the furnace bottom scaffold are integrally carried out to the operation floor 1 side by a lifting tool, workability is improved. Can do.

(4) In-furnace equipment assembly process (FIGS. 4-8, 9)
4 to 8, the internal space of the core shroud 2 is divided into an upper work area and a lower work area on the basis of the installation height position of the core support plate 30, and each of these work areas is accessed individually. The in-furnace apparatus assembly process which advances the assembly operation of the in-furnace apparatus is shown. Hereinafter, this process is divided into five processes and explained in order. In these processes, the internal space of the core shroud 2 is divided into an upper work area and a lower work area with reference to the installation height position of the core support plate 30, and each of these work areas is individually accessed to the reactor. An in-furnace equipment assembly process capable of proceeding with the assembly work of the internal equipment will be described.

(4-1) Installation of core support plate (CP) (Figs. 4 and 9)
FIG. 4 is an explanatory view showing a process of installing the core support plate 30 in the core shroud 2. In this step, as shown in FIG. 4, a core support plate 30 is suspended from above in the core shroud 2, and a fuel measurement grid is used by an operator from above the core support plate 30 by using a core measuring device 31. Perform core measurement. After the measurement, the core support plate 30 is fixed and attached (see symbol b1 in FIG. 9).

  In this in-furnace equipment assembly process, it is possible to perform the mounting work and measurement of the core support plate 30 by cooperative work in the upper work area and the lower work area described later.

(4-2) Mounting of differential pressure detector (DP), boric acid water injection (LC) piping, etc. (Figs. 5 and 9)
FIG. 5 shows the processing of the groove of the in-core monitor housing (ICMHsg) after the core support plate 30 is installed, the in-core monitor guide tube (ICMGT) 34 and the stabilizer 33, the differential pressure detector / boric acid water injection pipe 32, It is explanatory drawing which shows a process. FIG. 5 illustrates a situation where workers are respectively located in the upper work area and the lower work area, and the individual work proceeds for each area.

  In this process, the access route to the upper work area is the upper opening of the reactor pressure vessel on the operation floor 1 side above the core shroud 2, while the access route to the lower work region is opened to the lower part of the reactor pressure vessel 13. It is done as an opening in the recirculation outlet nozzle. That is, as described above, for example, the N1 nozzle 22 of the recirculation nozzle opened at the lower part of the reactor pressure vessel 13 is opened, and this recirculation nozzle has a size that allows an operator to pass through. The baffle plate 23 and the shroud support 19 have gaps that are large enough for an operator to pass through and communicate with the recirculation nozzle. Therefore, the worker can access the inside of the reactor pressure vessel 13 from the outside through the recirculation nozzle.

  Therefore, in the in-core equipment installation process of the present embodiment, after the core support plate 30 is installed, the upper work plate is installed in the upper work space and the work in the other upper space is performed in parallel with the upper work space. In the lower work area, the groove processing of the in-core monitor housing, the attachment of the in-core monitor guide tube, the attachment of the stabilizer 33 and the attachment of the differential pressure detector / borate water injection pipe 32 are performed (reference numerals c1, d1, FIG. 9). e1 etc.).

  As described above, in the process of the present embodiment indicated by reference numerals c1, d1, and e1 in FIG. 9, different in-core equipment is simultaneously performed in the upper work area and the lower work area in the core shroud 2 as an assembly work or the like. Therefore, the working time can be shortened in the device assembly process (see time T1 in FIG. 9).

(4-3) N1 nozzle plug installation, annulus water filling, recirculation pump (PLR) piping restoration (Figs. 6 and 9)
FIG. 6 shows that after assembling each of the above devices, the N1 nozzle 22 used as the access route in the lower region is attached with the N1 nozzle plug, the water filling the annulus (water 36), and the recirculation pump 20 (PLR) This shows the state where the pipe is restored.

  In this step, as shown in FIG. 6, the work in the lower work area of the core support plate 30 is completed, and preparation for installation of the next upper grid plate and the like is performed.

(4-4) Upper grid plate (TG) restoration (Figs. 7 and 9)
FIG. 7 shows a working state for restoring the upper grid plate. As shown in FIG. 7, the upper grid plate is installed on the upper ring of the core shroud 2, and the upper grid plate is suspended from above in the core shroud 2. Then, using the core measuring device 41, for example, the operator performs core measurement of the upper grid plate from above the upper grid plate, and after the measurement, the core support plate 30 is fixed and attached (see reference numeral f1 in FIG. 9). After this step, the temporary guide rod (GR) for in-furnace equipment guide (not shown) attached in the previous step is removed (see symbol g1 in FIG. 9).

(4-5) Removal of furnace wall seal, etc. (FIGS. 8 and 9)
FIG. 8 shows a state where the furnace wall seal is removed after each of the above steps. Thereafter, shielding is performed with water in the annulus portion (see symbol h1 in FIG. 9).

  After the above steps, surface modification of the brackets (CHS) (see symbol i1 in FIG. 9), restoration of the upper part of the furnace (see symbol j1 in FIG. 9), removal of the upper shield (see symbol k1 in FIG. 9), guide rod (GR) Restoration (see reference numeral 11 in FIG. 9), pre-use inspection (see reference numeral m1 in FIG. 9), inspection, etc. (see reference numeral n1 in FIG. 9) are performed, and the operation is completed.

(5) Comparison (FIGS. 9 and 10)
FIG. 9 shows work steps (a1 to n1) and reduced times (T1, T3) according to an embodiment of the present invention, and FIG. 10 shows work steps (a2 to n2) according to a conventional method corresponding to the present invention. And time (T1, T3). When comparing FIG. 9 and FIG. 10, in this embodiment, the internal space of the core shroud 2 is divided into an upper work area and a lower work area based on the installation height position of the core support plate 30. In the processes (c1 to e1) compared to the conventional process of sequentially working from the lower side to the upper side by individually accessing the work area and proceeding with the assembly work of the in-furnace equipment in parallel, Trial calculations revealed that the time can be shortened from T2 of the conventional example to T2 of the present embodiment.

  Although not shown, the work time is shortened also in the core shroud manufacturing process. Further, for the recovery of the furnace upper part, the working time is shortened from T4 of the conventional example to T3 of the present embodiment.

  Specifically, as a result of calculating the total number of days, the period from the production of the new core shroud 2 to the completion of the replacement work through the transportation into the core shroud 2 and the equipment assembly work shown in FIGS. 9 and 10 With regard to (excluding removal of the old shroud, etc.), the construction period is 72.5 days in the conventional example, whereas in this embodiment, it is 52.2 days, which can be shortened by about 20 days.

  In addition, according to the present embodiment, effects such as work reduction and high efficiency can be exhibited by the parallel work of manufacturing and transporting the core shroud 2 and mounting the equipment by dividing the work area.

  As described above, according to the present embodiment, it is possible to significantly shorten the period from the manufacture of a new core shroud to the transfer into the core shroud and the equipment assembly work until the replacement work is completed.

Sectional drawing explaining the core shroud manufacturing process in one Embodiment of this invention. Sectional drawing explaining the core shroud installation process in one Embodiment of this invention. Sectional drawing explaining the plate for carrying out the load support in one Embodiment of this invention. Sectional drawing explaining the in-furnace apparatus assembly process in one Embodiment of this invention. Sectional drawing explaining the in-furnace apparatus assembly process in one Embodiment of this invention. Sectional drawing explaining the in-furnace apparatus assembly process in one Embodiment of this invention. Sectional drawing explaining the in-furnace apparatus assembly process in one Embodiment of this invention. Sectional drawing explaining the in-furnace apparatus assembly process in one Embodiment of this invention. 2 is a time chart illustrating a method according to an embodiment of the present invention. The time chart which shows a prior art example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Operation floor, 2 ... Core shroud, 4 ... Crane, 5 ... Guide rail, 6 ... Wire, 7 ... Hook, 8 ... Water supply sparger inlet pipe, 9 ... Short ring, 10 ... Upper load support plate, 11 ... Lower Load support plate, 12 ... shroud suspension, 13 ... reactor pressure vessel, 14 ... shielding member, 15 ... control rod drive mechanism housing, 16 ... jack stand base, 17 ... jack, 18 ... pillar, 19 ... shroud support, DESCRIPTION OF SYMBOLS 20 ... Recirculation pump, 21 ... Diffuser, 22 ... N1 nozzle, 23 ... Baffle plate, 30 ... Core support plate, 31 ... Core measuring device, 33 ... Stabilizer, 32 ... Differential pressure detector, boric acid water injection piping.

Claims (8)

A core shroud replacement method in which a new core shroud is installed in a reactor pressure vessel from which the inside of the reactor has been derailed and the core shroud has been removed to assemble the in-core equipment, and the operation floor above the reactor pressure vessel A core shroud manufacturing process for manufacturing a core shroud and mounting a load supporting plate for the core shroud, and a core in which the manufactured core shroud is suspended from the operation floor and installed in the reactor pressure vessel. A shroud installation step, a load support plate unloading step for unloading the load support plate to the operation floor side after installation of the core shroud, and an inner space of the core shroud to determine the installation height position of the core support plate. As a reference, the upper work area and the lower work area are divided into each of these work areas. Core shroud replacement method characterized by comprising a furnace device assembly process of advancing the assembly operation of the furnace device by individually accessed is. In the core shroud manufacturing process, a water supply sparger inlet pipe is attached to the upper end portion of the core shroud, and in the core shroud installation process, the water supply sparger inlet pipe and the core shroud are integrated into the reactor pressure vessel. The core shroud replacement method according to claim 1, which is incorporated. The core shroud replacement method according to claim 1, wherein in the core shroud manufacturing process, all of the shroud assembly and outfitting are performed while the core shroud is fixedly arranged at a fixed position on the operation floor. In the core shroud manufacturing process, the height of the space above the floor is secured by mounting the water feed sparger inlet pipe by lowering the overall height except for a part of the lower end portion constituent material of the core shroud to be manufactured. The core shroud replacement method according to claim 1, wherein the lower end constituent material of the core shroud removed in the core shroud manufacturing step is connected to a shroud support member in the reactor in the core shroud installation step. 2. The load support plate as a fitting product is made up of a plurality of parts, and the load support plate made up of the plurality of parts is integrally carried out to the operation floor side in the load support plate unloading step. Core shroud replacement method. The access route to the upper work area in the in-reactor equipment assembly process is the upper opening of the reactor pressure vessel on the operation floor side above the core shroud, while the access route to the lower work area is the lower part of the reactor pressure vessel The core shroud replacement method according to claim 1, wherein the recirculation outlet nozzle is opened in the opening. 2. The core shroud replacement method according to claim 1, wherein in the in-core equipment assembly step, the core support plate is attached and measured by cooperative work in the upper work area and the lower work area. In the in-furnace equipment installation process, after the core support plate is installed, the upper work plate is installed in the upper work space and the work in the other upper space is performed in the upper work space. 2. The core shroud replacement method according to claim 1, wherein in the area, groove processing of the in-core monitor housing, attachment of the in-core monitor guide tube, attachment of the stabilizer, and attachment of the differential pressure detector / boric acid water injection pipe are performed.

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